Various apparatus for injecting a sealant material into a vehicle tire in order to seal the tire after a puncture are well known. Some of the systems also have an air compressor that performs the function of injecting the sealant into the vehicle tire to seal it and then inflating the vehicle tire to the proper pressure once the vehicle tire has been sealed by the sealant. One problem associated with these systems is how to inject the sealant into the vehicle tire. Some systems use gravity fed sealant injection devices, but these systems can not be used to inject sealant for any orientation.
Systems that can inject sealant at any orientation may use various techniques including pistons, bladders or a crushing a soft bottle with pressure. The piston-based sealant injection systems are desirable because the piston generates sufficient force to force all of the sealant out of the sealant container. However, the piston-based injection systems trade off piston sealing effectiveness with pressure drop.
One conventional system solves the problem of pressure drop vs. piston seal friction in a complicated way. In particular, as the piston nears the outlet, a barb punctures the piston which completely separates the piston friction from the pressure drop. However, the problem with this design is that it is complicated and it is very difficult to make a piston that can withstand high pressure without leaking, but at the same time be fragile enough to be punctured. Thus, it is desirable to provide a sealant dispenser that uses a piston, but overcomes the problem of the existing piston-based systems and it is to this end that the apparatus and method are directed.